Editing Virus classification (section)

=== Virus definition ===
The currently accepted and formal definition of a 'virus' was accepted by the ICTV Executive Committee in November 2020 and ratified in March 2021, and is as follows:<ref>{{cite journal|last1=Koonin|first1=Eugene V.|last2=Dolja|first2=Valerian V.|last3=Krupovic|first3=Mart|last4=Kuhn|first4=Jens H.|date=2021-09-01|title=Viruses Defined by the Position of the Virosphere within the Replicator Space|journal=Microbiology and Molecular Biology Reviews|volume=85|issue=4|pages=e0019320|language=EN|doi=10.1128/MMBR.00193-20|pmc=8483706|pmid=34468181}}</ref>

{{blockquote|Viruses ''[[sensu stricto]]'' are defined operationally by the ICTV as a type of [[Mobile genetic elements|MGE]] that encodes at least one protein that is a major component of the virion encasing the nucleic acid of the respective MGE and therefore the gene encoding the major virion protein itself or MGEs that are clearly demonstrable to be members of a line of evolutionary descent of such major virion protein-encoding entities. Any monophyletic group of MGEs that originates from a virion protein-encoding ancestor should be classified as a group of viruses.}}